Hydrophone array erection



Nov. 10, 1970 R. D. CRALL HYDROPHONE ARRAY ERECTION 2 Sheets-Sheet 1.

Filed Dec.

FIG.2

FIG.8

FIG.7

INVENTOR RUSSELL D. CRALL FIG. 6

BY A

ATTORNEY R. D. CRALL HYDROPHONE ARRAY ERECTION Nov. 10, .1970

2 SheetsSheet 2 Filed Dec. 16. 1964 FIG..3

Y 75 T N N. m E v H mm A x 3 E U .Y R B FIG. 5

United States Patent 3,539,979 HYDROPHONE ARRAY ERECTION RusselLD. Crall, Dallas, Tex., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Dec. 16, 1964, Ser. No. 418,786 Int. Cl. G01v 1/16 US. Cl. 340-7 3 Claims ABSTRACT OF THE DISCLOSURE A device is disclosed for supporting an array of seismic transducers which includes a plurality of support members which are prestressed to assume a nonplanar configuration. Means are provided for constraining the support members in this configuration and the supports may be released to permit them to unwind and extend radially from their central support. Transducers are attached at the ends of the support members. One or more central supports with the accompanying radial members may be provided.

This invention relates to a marine hydrophone array and more particularly to a hydrophone array erector.

In the establishment and operation of marine seismic listening stations, it is desirable to employ two and three dimensional arrays. At the same time it is desirable that the supporting system be unencumbered and as simple as possible. Thus, simplicity, while providing positive control over an array, is highly desirable. The present invention is directed to a system for erecting two dimensional and three dimensional arrays of sensors or hydrophones. The hyprophones are compactly packaged initially and are supported as to be lowered to operating depths below the water surface. At the operating depths, restraints placed on the members are removed so that the hydrophones will automatically be moved along a plurality of radially directed paths and will be rigidly supported by the propelling elements in a fixed two dimensional array. Two or more such units may be combined to form a three dimensional array. More particularly, in accordance with the present invention, there is provided a marine array erector in which a reel having a central member is provided for support of a plurality of sensors. Resilient strips each having one of the sensors mounted at one end thereof are each secured at the other end to the reel. Each strip is prestressed to assume a non-planar transverse configuration. Means are provided for restraining the strips in coil form with the sensors adjacent to the reel. A cable means supports the reel at a marine listening station at a selected depth below the water surface. Means are provided for releasing the coiled strips to permit them to unwind and form struts extending radially from the reel for the support of the sensors in an areal distribution.

For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a pair of sensor housings positioned at selected depths prior to array erection;

FIG. 2 illustrates the system of FIG. 1 with two arrays in operative positions;

FIG. 3 is a view partially in section of one of the units of FIGS. 1 and 2 in retracted form;

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3;

FIG, 5 is a view taken along lines 5-5 of FIG. 4;

FIG. 6 is a sectional view of one of the erecting elements of FIG. 2;

FIG. 7 is a modified form of an erecting element; and

FIG. 8 illustrates a further modification of the erecting elements.

Referring now to FIG. 1, a buoy 10 is adapted to be anchored by conventional means (not shown) at a marine listening station. A supporting cable 11 extends downward from the buoy 10 and provides vertical support for a pair of sensor housing units 12. and 13. Units 12 and 13 are supported one above the other at fixed positions on cable 11. An actuating cable 14 extends to the units 12 and 13 and may be in the form of a multi-conductor cable to provide a plurality of signal channels leading from sensors in the units 12 and 13. When the units 12 and 13, supported by cable 11, are at the selected listening depths below the surface 15, the cable 14 is reeled in sufficiently to elevate the units 12 and 13.

With units 12 and 13 elevated, four detectors 21-24, housed within the unit 12, are automatically moved radially outward to form an areal array. Cables 25-28 extend between detectors 21-24, respectively, and unit 12. The cables serve not only to provide vertical support for the detectors 21-24 but also provide electrical circuits which may then extend through cable 14 to the buoy 10.

The detectors 21-24 are mounted at the ends of the respective spring strips 31-34. The spring strips are made of thin material such as fiat beryllium copper which may be about four inches wide and five feet long. The strips are heat-treated into a tubular shape that is of such resilience that it can be wound flat on a central mandrel 35. Mandrel 35 is a part of a reel unit supported by the cable 11 and later to be described. Thus, when the housing unit 12 is elevated, the energy stored in the spring strips 31-34, wound spring-like on the mandrel 35, causes the detectors to be propelled outwardly. When the spring strips 31-34 are fully extended, they tend to assume their circular shape and thus form a three dimensional strut to hold the detectors 21-24 at uniform distances from the central mandrel 35. The cables 25-28 provide vertical components of support so that the array will be maintained in a substantially fixed relationship or configuration.

In a similar manner when the housing unit 13 is elevated, detectors 41-44, supported by strips 45-48 wound on the mandrel 49 with vertical supports by cables 51-54, form a second areal array.

The reel mechanism is best shown in FIGS. 3-5. As shown in FIG. 3, the cable 11 extends downwardly through a cap 60 or watertight junction box on housing 12. Cable 11 then extends centrally through a spool 61. A stop ring 62 is provided at the lower surface of the reel 61 so that the reel cannot slide downward on the cable 11. Similarly, a second stop ring 63 is provided near the upper surface of the reel 61 so that the reel is fixed in position on the cable 11.. The reel is provided with bearings for the support of central mandrel 35. Thus, the mandrel 35 is free to rotate relative to the frame of the reel 61. The spring strips 31-34 are each fastened to the surface of the mandrel 35 at the inner end thereof. The outer end of the spring strip 31 is wound around the detector 21 and thus is secured to detector 21 at the outer end of the spring strip. Strips 32-34 similarly anchor detectors 22-24. Four rollers 71-74 are mounted between the end plates of the reel 61 to facilitate unwinding of the spring strips 31-34. Guide plates 75-78 are provided with a contoured edge to accommodate the inner curved face of the spring strips 31-34, respectivly. Guide plates 75-78 cooperate with the rollers 71-74 in controlling the radial positions that the spring strips 31- 34 ultimately occupy when extended.

The cable 14 passes through the junction box 60 in the upper portion of the housing unit 12. The cable also extends downwardly through the central portion of the reel 61 along with cable 11. However, signal circuits are tapped into the cable 14 in the junction box 60. The separate cables 2 -28 forming such signal circuits extend from the lower surface of the junction box 60 to the respective detectors 2il-2i4.

In preparing for installation, the cables -28 are coiled or folded inside the housing unit 12. The spring strips 31-34 are wound onto the central mandrel 35 of the reel 61. The sidewalls '64 of the housing unit 12 are then telescoped downwardly over the detectors 2.1-24 and the reel 61, forming a compact package which may readily be lowered to the desired depth at the sensing location.

While the detectors have been shown restrained in their nested positions in FIG. 3 by the use of the housing unit 12, it will be appreciated that other restraining means may be employed. An electrically-actuated latching means, a ratchet-like dog on mandrel 315 releasable by tension on cable 14, or an explosively releasable band, may serve the purpose. In any event, one or more of the nested multi-detector units are lowered to a listening depth at a listening station. The nested detectors are then freed from their bonds and the spring strips are permitted to erect the arrays so that a two or three dimensional listening post is established. The signals from the detectors 21-24 and 41-44 may then be transmitted to the buoy 10. Signals therefrom may then be transmitted, if desired, from a suitable radio having an antenna 76 on a time sharing basis so that the listening station may be continuously monitored at a point remote therefrom.

In FIG. 5 the roller 74' and the guide plate 78 are shown in elevation. It will be noted that the plate 7 8 has a contoured surface 78a over which the inner face of the resilient strip 34 passes. The opposite or outer face of the strip 34 bears against roller 74 so that the strip 34 may be wound onto and unrelled from the center mandrel 35 along with the strips 31-33 which are provided with similar guide means.

The shaft 61a is secured to the bottom plate 61b and to the top plate 610, FIG. 3, to form a rigid frame. As shown in 'FIG. 5, the guide members are secured top and bottom to plates 61c and 61b, respectively, further to support the reel frame as well as provide guidance for the strips.

FIG. 6 illustrates one form of the strip 31. The strip as above noted is of spring stock which is heat-treated to a cylindrical configuration. As the spring strips are unrolled, each strip tends to roll into a circular shape, thereby providing a rigid strut for the support of the detectors. In FIG. 7, a modified form of the strut has been shown wherein two such spring strips 80 and 81 are joined together, back-toback, in the zone 82 to form a symmetrical beam or strut which may be rolled fiat onto a central roller. In FIG. 8, a further modification is shown in which a single spring strip 83 is provided with nesting ends 84 and 85'- to provide additional rigidity to a single strip over that available in the unit 31 of FIG. 6.

Thus, the present invention provides for the placing and support of sensors or hydrophones in an array or con figuration after the package has reached the operating depth in a marine environment such as in the ocean. For simplicity, four sensors or hydrophones in a horizontal plane are provided by each of the plurality of units. The detector spacing will be maintained by the resilient springlike struts which assume a three dimensional configuration as they are unrolled. When such struts are rolled in the form of a spring, they have a tendency to unwind. Thus, they provide their own erecting force once they are freed from restraining bonds. While two four-sensor arrays have been shown, almost any symmetrical or non-symmetrical configuration can be obtained in a package which is relatively small and easily handled when at the desired depth.

In order to provide an index to the relative positions of the various detectors, a magnetic or other direction-sensing device 88 may be mounted on the reel on which the strips Cir 31-34 are wound. The sensor, a conventional radio compass, for example, connected by cable 89' to the housing unit 12 will provide a signal which may be commutated to the transmitting antenna or to other monitoring equipment along with the signals from the detectors 21-24. In a similar manner, a direction sensor 90 coupled to housing 13 by cable 91 will provide a directional signal for the array of detectors 41-44.

It will be appreciated that the buoy 10 may be any one of many known constructions. It may not be anchored, in which case its location may be manitored along with the signals transmitted therefrom by radio-fix systems as are well known. The array of sensors may be varied in size as needed. In the example described above, the struts are about five feet long but size is no necessary limitation since larger or smaller arrays may be employed.

Where it is desirable to have the detector spacings which are appreciable with respect to the wavelength of the sound energy to be sensed, the arms or struts will be proportional thereto. Struts twenty-five feet or more in length may thus be used. Further, to add rigidity, a pair of struts may be employed for the support of each sensor with one strut above the other and with the sensor secured to the outer ends thereof and between them to hold the ends of the struts in spaced relation. Further, inorder to avoid flattening of the array when located in the presence of currents, lines 9 2 and 93 extend from detector to detector in peripheral loops around each array. As shown in FIG. 2, line 92 is connected to the detectors in the upper array and line 93 serves to add support to the lower array.

In accordance with a modification of the invention, the frame may have a central mandrel which is fixed rather than rotatable as above described. In such case, the several resilient struts would be wound around the respective detectors. Such struts may readily be visualized by reference to FIG. 4. For example, the strip 31 would be coiled around detector 21. The remaining strips 32-34 similarly would be coiled around detectors 22-24. The resultant package of detectors with strips coiled therearound would then be bound to prevent the strips from uncoiling until the unit is located at the operating depth. Thereupon, the restraints would be loosed so that the array would erect itself. Supporting cables corresponding to 25-27 would be provided to stabilize this modification.

Thus, in accordance with the invention, a marine seismic detector array erector is provided with a central support structure. A plurality of sensors are mounted at the ends of elongated resilient strips. One end of each of the strips is secured to the central support. Each strip is prestressed to a non-planar transverse configuration. The strips have been shown as circular in form in FIGS. 6-8, but they may be of S-shape or may have other shapes which will cause the strips to assume a beam-like or three dimensional configuration. Means are provided for restraining the strips when wound into coil form to hold the sensors adjacent to the central support. A cable is provided for supporting the system at a selected depth at a listening station. Means are provided for releasing the restraints on the detectors and strips, to permit the strips to unwind and to form struts which extend radially from the central structure to support and maintain the sensor in an areal distribution.

Having described the invention in connection with certain specific embodiments thereof, it is to be understood that further modifications may now suggest themselves to those skilled in the art, and it is intended to cover such modifications as fall within the scope of the appended claims.

What is claimed is:

1. A marine seismic detector array with a self erector which comprises:

(a) a pair of plates having a central shaft extending therebetween,

(b) a rotatable hub mounted on said shaft,

(c) a plurality of resilient strips prestressed to a nonplanar transverse configuration each anchored at one end thereof to the surface of said hub and wound onto said hub,

(d) a like plurality of guides secured between said plates radially spaced from said hub and through which said strips extend,

(e) cable means for supporting said plates at a preselected depth at a marine listening station,

(f) a seismic sensor secured to the free end of each of said strips with said strips normally coiled about said hub,

(g) a restraining band encircling the sensors to prevent said strips from unwinding from said hub, and

(h) actuating means for removing said band to permit said strips to unwind from said hub for the support of said sensors in an array wherein each of said sensors is spaced from the axis of said hub.

2. A marine seismic detector array with a self erector which comprises:

(a) a pair of plates having a central shaft extending therebetween,

(b) a rotatable hub mounted on said shaft,

(c) four resilient strips prestressed to a non-planar transverse configuration each anchored at one end thereof to the surface of said hub and wound onto said hub,

(d) four pairs of equally spaced guides secured between said plates radially spaced from said hub and through which said strips extend,

(e) cable means for supporting said plates at a preselected depth at a marine listening station,

(f) a seismic sensor secured to the free end of each of said strips with said strips normally coiled about said hub,

(g) a restraining band encircling the sensors to prevent said strips from unwinding from said hub, and

(h) actuating means for removing said band to permit said strips to unwind from said hub for the support of said sensors in an array wherein each of said sensors is spaced from the axis of said hub.

3. A marine seismic detector array with an erector which comprises:

(a) a support structure having a central member,

(b) a plurality of sensors,

(c) elongated resilient strips each having one of said sensors secured at one end thereof and secured at the other end to said structure, each of said strips being prestressed to a non-planar transverse configuration,

(d) a band encircling said sensors and said structure for restraining each of said strips wound into coil form with said sensors adjacent to said structure,

(e) cable means for supporting said structure at a listening station at a selected depth below a water surface, and

(f) a second cable means for applying to said band a sensor releasing force to release said band to permit said strips to unwind and form struts extending radially from said structure for the support of said sensors in an areal distribution.

References Cited UNITED STATES PATENTS 3,025,608 3/1962 Hendrix 24284.8 X 3,141,148 7/1964 Hueter 340-9 3,144,104 8/1964 Weir et a1. 18934 RICHARD A. FARLEY, Primary Examiner B. L. RIBANDO, Assistant Examiner US. Cl. X.R. 

